Sealing means for the driving shaft of cycloidal boat propellers



Feb. 10,- 1959 G. FRANZ SEALING MEANS FOR THE DRIVING SHAFT OF CYCLOIDAL BOAT PROPELLERS Filed May 23, 1955 fig. 1

2 Sheets-Sheet 1 INVENTOR.

ebb/THEE FRANZ Feb. 10, 1959 G. FRANZ 2,872,891

SEALING MEANS FOR THE DRIVING SHAFT 0F CYCLOIDAL BOAT PROPELLERS Filed May 25, 1955 2 Sheets-Sheet 2 III,

INVENTOR. GMT/15R FRANZ A TTORNEYS United States Patent O SEALING MEANS FOR THE DRIVING SHAFT F 'CY'CLOIDAL BOAT PROPELLERS Gunther Franz, Heidenheim (Brenz), Germany, assignmto J. M. Voith G. 111. b. H., Maschinenfabrlk, Herden- I heim (Brenz), Germany, a corporation of Germany Application May 23, 1955, Serial No. 510,328 In Germany October 1, 1948 Public Law 619, August 23, 1954 Patent expires October 1, 1968 11 Claims. (Cl. 115-50) This invention relates to sealing means for the driving shaft of cycloidal propellers in vessels and, in particular, to such propellers being located at a low depth relative to the water line.

In vessels driven by means of cycloidal propellers sealing means are provided at the point where the propeller shafts pass through the propeller housing which sealing means consist in particular of grease-lubricated carbon packing rings, which prevent on the one hand the penetration of water from the propeller chamber to the oilfilled transmission case or into the interior of the vessel, and on the other hand losses of oil from the transmission case. During normal operation of the propeller a special centrifugal pump provided at the circumference of the impeller serves for emptying the propeller casing and thereby for relieving the sealing.

Both the sealing means and the impeller pump were hitherto provided in all constructions independent of the fact whether the propeller has a great or small depth position. The sealing means were extraordinarily expensive due to the large diameter on which they had to be arranged. Furthermore, they often were the cause of disturbances and interruption of operation. They had to be disassembled for repair which was only possible after removing the propeller due to lack of accessibility of the sealing means.

In order to avoid these drawbacks, my invention provides in the case of propellers having a small depth position, in particular in vessels having a square tuck that the casing surrounding the propeller, hereinafter called the propeller well, is fitted with a collar protruding from the water line and surrounding the propeller shaft, which collar forms at its upper end a narrow gap with the propeller shaft. According to a further feature of the invention the sealing means of the oil-filled transmission case (for instance a bevel gear casing) against oil losses is arranged independently of the aforesaid sealing collar and spaced therefrom. The aforesaid sealing means is for instance shaped as an oil-collecting groove which is provided with an outlet, and located below the large bevel gear, surrounding the upper end of the propeller shaft and forming a gap therewith.

The gap between the oil-collecting groove and the propeller shaft may be covered against the gap between the shaft and the upper collar end by a cup surrounding the upper end of the sealing collar and connected with the propeller shaft. Furthermore, a collecting groove is preferably provided on the outside of a stationary sealing collar which groovehas an outlet to the bilge. According to a preferred modification of the invention the upper end of the sealing collar itself is shaped as a collecting groove having corresponding blades traversing the aforesaid groove labyrinth-like and being connected with the shaft or with a bevel gear flange mounted on the same. In order to provide suflicient space between the impeller of the propeller and the gear (transmission casing) for the sealing collar, the large bevel gear conpeller cavity 13. There is a "ice neeted with the shaft is arranged with the driving pinion below the same, according to a further feature of the invention.

It is, therefore, the principal object of this invention to provide an improved sealing arrangement for marine propeller shafts.

'It is another object of this invention to provide a simple, yet effective, sealing arrangement especially adapted for sail wheel propeller shafts.

It is a further object of this invention to provide a sealing arrangement for a marine propeller shaft wherein the transmission casing oil seal is separate and independent from the shaft water seal.

Other objects and advantages of this invention will be come apparent upon reference to the accompanying de scription when taken in conjunction with the following drawings wherein: I

Fig. 1 is a vertical sectional view illustrating the shaft sealing arrangement of this invention;

Fig. 2 is a sectional view similar to that of Fig. 1 and illustrating a modification of the invention; and

Fig. 3 is a sectional view similar to that of Figs. 1 and 2 showing a further modification of this invention.

Proceeding now to the drawings, more particularly to Fig. 1 wherein like reference symbols indicate the same parts throughout the various views, 10 indicates the bottom of the hull of a vessel equipped with the propeller sealing arrangement of this invention. Displacement of the vessel is revealed by the location of the water line indicated at 11 with respect to the hull bottom. A casing 12 is recessed within the hull bottom 10 to form a propropeller shaft opening 14 in the casing 12.

Disposed within the propeller cavity 13 is an impeller 15 of the propeller. The impeller 15 is mounted upon the lower end of a hollow propeller shaft 16 which extends upwardly through the propeller shaft opening 14. The hollow shaft 16 is mounted upon a bearing support 17 which projects into the hollow propeller shaft.

At the upper end of the hollow shaft 16 there is an external flange 18 having a downwardly opening annular groove 19 therein. A bevel gear 20 having downwardly directed teeth 21 is mounted upon the upper end of the propeller shaft immediately above the external flange 18. The bevel gear 20 is drivingly engaged by a pinion gear, such as illustrated in Fig. 3.

Bevel gear 20 and its cooperating pinion gear are enclosed in a bevel gear case 22 having an opening 23 therein, through which passes the propeller shaft 16. A ring-like member 24 having an angular cross-section is secured within the case opening 23. The member 24 has an inner diameter which is only slightly greater than the outer diameter of the hollow shaft 16. There is an upstanding flange 25 within the gear case surrounding the propeller shaft opening 23. Flange 25 is spaced from a leg of the ring-like member 24 to form a collector space for oil dripping from the bevel gear case 22.

A conduit 27 is employed to drain the oil from the collector space 26 and convey the oil to a circulating pump which returns the oil to the bevel gear case. In order to provide a separate seal against the leakage of water into the gear casing, a collar-shaped drum 28 is provided which extends upwardly to a point immediately below the ring-like member 24. At the upper end indicated at 29 of the collar 28 there is an internal shoulder 30 which cooperates with an annular shoulder 31 on the outer surface of the hollow propeller shaft 16. These two shoulders cooperate by their proximity short of contact and are separated by a small sealing gap indicated at 32. A protecting downwardly opening cup-shaped member 33 is mounted upon the hollow propeller shaft 16. The cylindrical wall of member 33 extends outwardly beyond the collar 28; There is a depending external flange 34 on the protecting ring which is in telescoping relationship with the collar 28. The protecting ring 33 serves to prevent the passage of any water through the sealing gap 32 up into the. bevel gear case. Any water passing through the sealing, gap 32 may be deflected downwardly outside of the collar-shaped drum. 28 into a collector space 35 formed by a tubular member 36 positioned upon a flange-like portion 37 at the base of the collar 28. The collector space 35 is drained by a con duit 38 which conveys the water to the bilge of the vessel.

When power is being transmitted to the propeller, the propeller cavity 13 is kept free from water by centrifugal action of the impeller 15. However, when the rotation of the propeller ceases, water will enter the propeller cavity to the height of the water line 11. Under normal conditions this water line will be below the sealing cap 32. Consequently, there will be no penetration of the water into the gear case.

In the event that the water line should rise above the sealing gap 32, the protector-ring 33 will divert the water downwardly into the collector space 35 where it is pumped into the bilge. The bilge pumps which are part of the standard equipment of ships will then function to drain the bilge in a normal manner.

When the vessel is under way, water spray is prevented from. passing through the sealing gap 32 into the oil collector space 26 by the action of the protector ring 33.

It will at once be apparent that any oil which may leak from the bevel gear casing is prevented from contacting the water sealing means. Leaking oil is collected within the collector space 26 and drained by the conduit 27 to be recirculated throughout the gear case.

Proceeding now to Fig. 2, there is illustrated therein a modification of this invention which is especially adapted for use with a propeller shaft which is somewhat shorter in length than the propeller shaft in the first described embodiment of the invention. In this modification the leakage oil collector space 26 is positioned laterally of the sealing gap 32. Water sealing means, as represented by the sealing gap 32, and the oil collector space 26 are separated from each other by means of an annular portion 39, which depends from the downward face of the bevel gear 20. This annular portion 39 functions similarly as the protector ring 33. The annular portion 39 also serves to divert water passing through the scaling gap 32 from entering the oil leakage collector space 26 by diverting the water downwardly into the collector space 35 from whence it is pumped into the bilge. Therefore, by positioning the oil collector space 26 laterally of the water sealing gap, a more compact propeller drive arrangement is possible through the use of ashorter propeller shaft.

Proceeding now to Fig. 3, there is illustrated therein another modification of this invention. In this modification the propeller shaft 16 is similarly surrounded by a collar 28. However, the upper end of the collar is modified by positioning an external shoulder 40 thereon. An axial groove 41 is formed in the outer edge of the shoulder 40. This groove 41 cooperates with a dependent portion 42, which projects from the lower face of the bevel gear 20 into the groove 41. There are a plurality of openings 43 in the bottom of the axial groove 41. Suitable conduit means as indicated at 44 are provided to convey liquid from the groove 41 to the bilge of the vessel.

In this modification, the gear case as indicated at 45 substantially surrounds the water sealing means comprising the axial groove 41 and its cooperating annular portion 42. The level of the oil within the casing is maintained at a low level with respect to the upper end of the collar 28. Consequently, there is little likelihood of the lubricating oil escaping into the propeller cavity by passing over the upper end of the drum member 28. Furthermore, any oil passing over the top of the drum will be trapped in the axial groove 41. Any oil accumulated within the groove will be of a negligible amount so that no substantial loss will result by pumping the oil together with any water into the bilge of the vessel through the conduit 44.

A small feed pump 46 is mounted upon the pinion driving shaft indicated at 47. The pump 46 serves to maintain the level of the oil within the gear casing at a levelwhich will be sufficiently low to prevent the oil from escaping over the top of the collar-shaped drum 28.

Thus it can be seen that the present invention provides a propeller shaft arrangement wherein the oil and water sealing means are separate and independent from each other. The entire structure is simple, yet effective, to prevent the water from entering the oil collector space and similarly the oil from entering the water collector space. The oil leaking from the bevel gear casing is collected for recirculation through the-casing. Water seeping into the vessel through the propeller shaft is pumped to the bilge from where it is disposed of in a normal manner.

The compact arrangement of the sealing structure permits the propeller driving structure to occupy a minimum of space in the hold of the vessel. Furthermore, since both the oil and water sealing means do not involve contact with bearing surfaces, the problems involved in maintaining this propeller arrangement in good working condition are considerably reduced.

It will be understood that this invention is susceptible to modification in order to adapt it to different usages and conditions, and, accordingly, it is desired to comprehend such modifications within this invention as may fall within the scope of the appended claims.

What I claim is:

1. In a vessel driven by cycloidal propellers being positioned at a low depth relative to the waterline and having a driving shaft disposed substantially vertically relative to the waterline, an impeller, an impeller housing, and an oil-filled bevel gear transmission case; in combination first sealing means for said driving shaft comprising an integral elongated collar having an upper open end, said collar projecting above the waterline and surrounding said driving shaft so as to form a free chamber between the latter and said collar, and a narrow gap between the shaft and said upper open collar end, said collar being stationary with its lower end mounted on said housing, below the waterline when the vessel is in horizontal position; a downwardly opening cup-shaped member covering the upper end of said stationary sealing collar; and second sealing means for said transmission case, said sealing means being provided with an oil-collecting groove having an outlet and surrounding the upper end of said driving shaft so as to is connected with the driving bevel gear in said gear transmission case.

4. In a vessel, in combination, a cycloidal propeller having a hollow driving shaft passing substantially vertically through the bottom of said vessel and an impeller secured to the lower end of said shaft; bearing means extending into said hollow driving shaft and engaging the inner surface thereof for supporting said shaft for rotation about said bearing means; sealing means for preventing the'ingress of water into the interior of said vessel, said sealing means comprising an elongated collar having an upper open end,-said collar projecting upwardly above the waterline of the vessel and surrounding the outer surface of said driving shaft in such a manner that throughout the entire axial length of said collar an annular chamber is formed between said outer surface of said shaft and the inner surface of said collar; a bevel gear mounted on said driving shaft for rotation therewith, said bevel bear being arranged in the region of the upper end of said driving shaft and being formed on its underside with teeth adapted to mesh with a driving pinion; and a shaft carrying a driving pinion meshing with said bevel gear, said last mentioned shaft being arranged in the space between the bottom of said vessel and a horizontal plane passing through said upper end of said hollow driving shaft.

5. In a vessel, in combination, a cycloidal propeller having a hollow driving shaft passing through the bottom of said vessel and an impeller secured to the lower end of said shaft; bearing means extending into said hollow driving shaft and engaging the inner surface thereof for supporting said shaft for rotation about said bearing means; and sealing means for preventing the ingress of water into the interior of said vessel, said sealing means comprising a collar which is secured at its lower end to the bottom of the vessel, which projects upwardly above the water line of the vessel, and which surrounds the outer surface of said driving shaft in such a manner that throughout the entire axial length of said collar an annular chamber is formed between said outer surface of said shaft and the inner surface of said collar.

6. In a vessel, in combination, a cycloidal propeller having a hollow driving shaft passing substantially vertically through the bottom of the vessel and an impeller secured to the lower end of said shaft; hearing means extending into said hollow driving shaft and engaging the inner surface thereof for supporting said shaft for rotation about said bearing means; a transmission case adapted to contain oil surrounding the upper portion of said shaft; first sealing means for preventing the ingress of water into the interior of the vessel, said first sealing means comprising a collar which is secured at its lower end to the bottom of the vessel, which projects upwardly above the water line of the vessel, and which surrounds the outer surface of said driving shaft in such a manner that throughout the entire axial length of said collar an annular chamber is formed between said outer surface of said shaft and the inner surface of said collar; and second sealing means independent of said first sealing means and arranged in spaced relation relative thereto for sealing said transmission case with respect to said shaft.

7. The combination defined in claim 6 wherein said second sealing means are provided with an oil-collecting groove having an outlet and surrounding the upper end of said driving shaft so as to form a gap therewith.

8. In a vessel, in combination, a cycloidal propeller having a hollow shaft passing substantially vertically through the bottom of the vessel and an impeller secured to the lower end of said shaft; a housing for said impeller; bearing means extending into said hollow driving shaft and engaging the inner surface thereof for supporting said shaft for rotation about said bearing means; a transmission case adapted to contain oil surrounding the upper portion of said driving shaft; sealing means for preventing the ingress of water into the interior of the vessel, said sealing means comprising a collar which is secured at its lower end to said housing, which projects upwardly above the water line of the vessel, and which surrounds the outer surface of said driving shaft in such a manner that throughout the entire axial length of said collar an annular chamber i formed between said outer surface of said shaft and the inner surface of said collar, said sealing means further comprising a downwardly opening cupshaped member covering the upper end of said collar; and a sealing device for said transmission case, said sealing device being arranged independently of said collar in spaced relation thereto.

9. In a vessel, in combination, a cycloidal propeller having a hollow driving shaft passing substantially vertically through the bottom of the vessel and an impeller secured to the lower end of said shaft; bearing means eX- tending into said hollow driving shaft and engaging the inner surface thereof for supporting said shaft for rotation about said bearing means; a transmission case adapted to contain oil surrounding the upper portion of said shaft; first sealing means for preventing the ingress of water into the interior of the vessel, said first sealing means comprising a collar which is secured at its lower end to the bottom of the vessel, which projects upwardly above the water line of the vessel, and which surrounds the outer surface of said driving shaft in such a manner that throughout the entire axial length of said collar an annular chamber is formed between said outer surface of said shaft and the inner surface of said collar; and second sealing means for sealing said transmission case with respect to said shaft, said second sealing means comprising an upwardly opening annular groove carried by said collar at the upper end thereof and downwardly projecting annular means carried by said shaft and cooperating with said groove to form a labyrinth-like passage.

10. The combination defined in claim 9 wherein an outlet conduit is provided for connecting the bottom of said groove with the bilge of the vessel.

11. In a vessel, driven by a cycloidal propeller having a sealing as described in claim 9, and a bevel gear drive, said bevel gear drive comprising a drive bevel gear connected to the shaft of said propeller, said drive bevel gear having downwardly directed teeth, and a pinion, said pinion being arranged below said drive bevel gear.

References Cited in the file of this patent UNITED STATES PATENTS 97,655 Lebby Dec. 7, 1869 1,772,095 Altorfer Aug. 5, 1930 1,810,371 Baumann June 16, 1931 2,393,691 Karassik Jan. 29, 1946 FOREIGN PATENTS 368,440 Italy Feb. 15, 1939 402,145 Italy Feb. 19, 1943 721,401 France Dec. 22, 1931 

